The Big Gaping Hole in Materialism Atheists are caught between two things. On hand, they are given an incentive. An atheist might give one of those strangely pious-sounding lectures on "good without God" for PR purposes- but beneath the surface- they know: atheism gives them a license to do whatever they want. They might deny this for political reasons- they know, though. This is the inescapable conclusion of moral relativism which they don't deny atheism leads to.
On the other hand, atheism leads to the conclusion that life is meaningless. — Ram
Firstly, the claim that "atheism gives them a license to do whatever they want" would require a separate argument as it is not self-evident to me: While atheism might not give behavioural prescriptions, it does not rule out other sources of behavioural rules. I fail to see how it would grant any license at all. What those other (subjective/intersubjective/objective) sources of morality might be, is discussed in large parts of moral philosophy and ethics and there is no need (and not enough space) to repeat that discussion here. (20-50 years of study would not be enough. And I'm sorry to say that, but if you think that you have grasped it all, then I'm inclined to think that you have not understood it. This is meant as an expression of my hesitation to take your word on that, not as a judgement of your intelligence.)
Secondly, the claim that "atheism leads to the conclusion that life is meaningless" seems to require a very thorough argument as well: Again, atheism might not provide a meaning for your or anyone's life, but it does not rule out meaning either. And again whatever you might intend by 'meaning' can have sources elsewhere. (I personally have found sources for both morality and meaning--albeit subjective.)
Therefore, although you seem to imagine atheism to be a dark and desolate place, it is not necessarily so. Yes, it might require some work to establish all of those things. (It's worth the time and thought for me at least. And I don't see anyone solving the theodicee problem anytime soon.)
I apologize for not addressing all of your points, but it seems to me that they all would require some work in their exposition to warrant a proper debate.